Fuse construction



March 1, 1955 R. P. SANT 2,703,349

FUSE CONSTRUCTION Filed Aug. 27, 1953 3 Shets-Sheet 1 RALPH P. SA NTJNVENTOR.

ATTORNEY March 1, 1955 R. P. SANT 2,703,349

FUSE CONSTRUCTION Filed Aug. 27, 1953 3 Sheets-Sheet 2 RALPH P. SANTINVENTOR.

ATTORNEY March 1, 1955 P, SANT 2,703,349

FUSE CONSTRUCTION Filed Aug. 27, 1953 I 3 Sheets-Sheet 3 I26 I27 I30 useRALPH P. SANT INVENTOR.

ATTORNEY United States Patent FUSE CONSTRUCTION Ralph P. Sant, SouthMilwaukee, Wis assignor to McGraw Electric Company, Milwaukee, Wis., acorporation of Delaware.

Application August 27, 1953, Serial No. 376,818

6 Claims. (Cl. 200-113).

This invention relates to improvements infuse construction.

Cut-outs heretofore made by those skilled in the art have generallyincluded two spaced terminals normally insulated from each other andhaving means for electrically connecting the terminals, swingablymounted therebetween. Frequently the electrical connecting memberconsists of an expulsion tube having therein a fusible section joining acontact at the lower end of the tube with a durable or expendible cap atthe upper end of the tube. The contact at the lower end of the tube isusually pivotally carried through a system of linkage to enable the fusetube to be swung to closed circuit position and to facilitateself-disconnecting if the fusible section ruptures due to excesscurrent. Force necessary to urge the fuse tube to drop out after thefusible section ruptures may be derived from resiliency in the uppercontact. Sufficient time delay to allow the fusible section to burnclear before the fuse tube drops out is effected by the propulsion ofthe tube against the upper contact spring for the duration of expulsionof the expanding gases from the lower end of the tube.

It is apparent from the foregoing remarks that to complete an electricalcircuit through a fuse cutout construction the current must flow througha multiplicity of relatively stationary and relatively movable parts. Toreduce the ohmic resistance which occurs as a natural consequence of thecurrent flowing between the parts of a cut-out, designers usually resortto use of heavy castings, usually of brass or bronze. High resistancejoints between the moving parts are then often shunted by a highlyconductive flexible means to minimize joint resistance. But, since thefuse tube connecting the terminals is generally removable there willalways remain at least one electrical junction at each terminal whichcannot be solidly connected to the movable conductive member.Consequently, it is desirable to employ means to reduce this joint re.-sistance to a bare minimum.

Despite the heavy castings generally employed to comprise the terminalsof the fuse cut-out constructions known to the art, little has beenaccomplished to assuresmooth operation and accurate alignment betweenthe fixedterminals and the movable contacts when'the'cut-outis urged toclosed position. The conductive member which connects the fixedterminals often has a. tendency to. rock laterally on its pivotalsupports: and a tendency to. creep out of the hook-like bearings. Thisis a frequent cause of annoying misalignment and jerky motion evidentwhen the usual cut-out is being operated;

To obviate the foregoing undesirable features found in conventional fuseconstructions this invention has as one of its objects to provide acut-out using: low cost materials having high mechanical strength andcomparatively .low electrical conductivity merely as a structuralsupport A. further object of this invention is to employa lower shuntcontact embodied in the circuit through the. fuse construction in suchmanner as-to effect high electrical tube when in open'circuit position.-v

conductivity without interfering with removal-of the fuse "ice A stillfurther object is to spring bias the lower contact shunt for the doublepurpose of maintaining electrical contact between relatively movableparts and to urge the trunnions upon which the fuse tube pivots intopositive seating engagement with the hook-like bearings of the lowerterminal.

A still further object is to provide an arc baflie which adequatelyprotects the parts of the fuse construction from the erosive effects ofthe hot gases evolved incidental to rupture of the fusible sectionwithin the fuse tube.

Other objects will appear within the following description.

Embodiments of the invention are shown in the accompanying drawings, inwhich:

Fig. l is a side elevation showing one form of the invention, such viewshowing an open type of a cut-out in the form of a drop-out fuse.

Fig. 2 is a plan view relative to the upper end of Fig. 1.

Fig. 3 is a view taken on the line 33,of Fig. 1 showing the uppercontact support.

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 1 showing thelower cartridge contact assembly.

Fig. 5 is a sectional view taken on the line 5-5 of Fig. 1 showing thelower contact and link assembly with the bifurcated connector boltremoved.

Fig. 6 is a side elevation view showing an alternative embodiment of anupper contact support.

F Fi,%. 7' is a sectional vieW taken on the line 77 of Referring to Fig.1 it will be seen that the device comprises an elongated insulator 1supported intermediate its ends by a strap 2 held by a bolt 3 passingthrough insulator 1 and provided with upper and lower terminalsindicated generally by the reference characters 4 and 5 respectively.

The upper terminal 4 is preferably secured to insulator 1' by a bolt 6and the lower terminal 5 is secured by welding to a clamping band 7.Lower terminal 5 comprises a back plate 8 arcuately shaped to conform tothe contour of the clamping band 7. Two spaced side plates 9 butt theback plate 8 at right angles and may be integral with the back plate orwelded thereto. These may be of metal having an electrical conductivitywhich is low compared to pure copper for reasons which will be explainedlater. Depending from each side plate 9 is a hooklike portion 10 whichhas an embossed portion 11 following the curvature of the outer marginof the hook-like portion to serve as a means to stiffen and reinforcethe side plate. The hook-like portion 10 defines an arcuate bearingsurface or trunnion receiving portion 12 having its axis in alignmentwith a similar bearing surface spaced laterally a distance equal to thewidth of back plate 8. A cover plate 13 is shaped to fit the contour ofthe side plates. 9 and may be welded thereto or formed of one pieceintegrally therewith. Cover plate 13 is bifurcated at its outer end toform prongs 14 disposed equidistant about the center line of the coverplate to define a slot 15 having a flared entrance 16.

Though the entire lower hinge assembly has been described as beingcomposed of a number of parts it should be readily apparent that it maybe easily stamped from a single piece of metal and bent thereafter toform a boxlike structure having an open bottom and front. Hence, only asingle joint on the center line of the cover plate '13 need be welded.

A terminal mounting strap 21 is imposed upon the back plate 8 interiorlyof the lower hinge assembly and may be riveted to the back plate orstamped integral therewith. Strap 21 is bent toward the center line ofsupporting insulator 1 to form a flat portion 22 having two crescentshaped holes 23 for receiving a bifurcated bolt connector 24 engageablewith a load wire (not shown). A flat reinforcing spring 27 bears uponthe flat end portion 22 and is securedv thereto by a rivet 28. A contactshunt 29 of Phosphor bronze having its end portion 30 bent upon itselfis superposed upon the reinforcing spring 27. Rein.- forcing spring 27,contact shunt 29 and end portion 22 are all perforated by congruentcrescent shaped holes 23 and are held insecure electrical contactbytightening. nut 25 v on bifurcated bolt connector 24.

A drop-out fuse tube is provided as indicated by the reference character35. Fuse tube 35 is equipped at its lower end with a split sleeve likeclamp 36 which fits tightly around the fuse tube and may be pinnedthereto. Clamp 36 is formed with two spaced integral lips 37 bent toextent radially in parallel relative to a vertical plane coincident withthe axis of the arcuate portion of clamp 36. Two holes 38 receive bolts39 which urge lips 37 toward each other to contribute to the clampingforce on tube 35.

A U-shaped cartridge contact support referred to generally by referencecharacter 45 embraces the lips 37 of clamp 36 and is rigidly held inengagement therewith by the bolts 39 extending through holes 38a of thesupport 45. Contact support 45 may be formed of any ferrous or poorlyconducting metal as is also the case with tube clamp 36 because neitherpart is relied upon to carry current. In examining support 45 it will beseen to consist of a flat piece of metal bent back upon itself to form aU-shaped piece. The sides 46 of sup port 45 are spaced from each otherin a vertical plane and have their lower margins bent outward to formsymmetrical shoulders 47. These shoulders are bent downward again at aright angle to form vertically extending skirts 48 spaced parallel toeach other equidistant from a vertical plane midway between sides 46.The sides 46 are perforated by a large hole 4-9 engageable by ahookstick (not shown) when the fuse has been pivoted to open circuitposition. Skirts 48 freely receive a pivot pin 55.

A lower contact referred to generally by numeral 56 is linked pivotallyto the cartridge contact support 45 by means of pin 55. Lower contact 56consists of a channel shaped member 57 having a countersunk hole 58through each leg 59. Pin 55 carries channel 57 and is prevented frommoving laterally by peening its ends 55a into the countersunk holes 58.The legs 59 extend vertically upward from the bottom 62. of channel 57and also have depending portions 63 integral with the legs. Eachdepending portion 63 has a hole 64 in lateral alignment with the otherthrough which a trunnion pin 55 is pressed and peened into place. Thebottom 62 of channel 57 is also extended in a direction opposite fromthe depending portions 63 to form a gas baffie 70 which curves upwardgenerally from bottom 62. Baffle 70 is bent arcuately across its widthto a radius substantially conforming to that of fuse tube 35. When thebaffle 70 is in its normal position, maintained while the fuse tube 35is in its closed circuit position, its end 70a bearsagainst the lowerend of the lower tube clamp 36. It thereby performs the triple functionof preventing the lower contact 56 from rocking over center, ofdeflecting the hot gases incidental to rupture of the fusible section(not shown) within fuse tube 35 and of ejecting the leader 69 on thefusible section.

A contact cam 74 is located between the legs 59 of the channel member57. Cam 74 is substantially S-shaped and is formed of a highlyconductive flat metallic piece which bears upon the bottom of channel 57and is secured thereto over a fiat bearing area 75. A flat headedshoulder bolt 76 passes through a hole 77 in cam 74 and the bottom ofchannel member 57. The bolt 76 is brazed (not shown) to cam 74 andbottom of channel 57 to assure permanent positioning and good electricalconnection of the parts. A knurled nut 78 is screwed on bolt 76 for thepurpose of electrically connecting a fuse link leader 69 which dependsfrom the fuse tube 35.

The upper end of fuse tube 35 is provided with an upper contact 86consisting preferably of copper or bronze. Contact 86 comprises a hollowtubular body member 87 which fits snugly over the outer periphery offuse tube 35 and may be pinned thereto by any suitable means. The upperpart of tubular body member 87 has a neck portion 88 integral therewithfor receiving a closure cap 90. This cap may be of the solid variety orthe frangible type which fractures when subjected to excessive pressuresdue to gases being generated within the fuse tube.

An eye 93 is cast integral with the tubular body member 87 and extendsradially therefrom for the purpose of engaging a hook-stick (not shown)when it is desired to swing the fuse tube on trunnions 65.

Diametrically opposite of eye 93 and also integral with tubular body 87is a web 94 which carries a round of a plane coincident with the eye 93.A guide pad 96 protrudes radially upward from rod intermediate its endsto form shoulders 97 which rise vertically and are parallel to eachother.

An upper fixed terminal 4 consists of an upper contact support 101fastened to insulator 1 by a bolt 6 which passes through an elongatedhole 102 in back plate 103. A gasket of any resilient material ispreferably placed between the back plate 103 and insulator 1 though itis not shown in the views. Providing back plate 103 with an elongatedhole 102 permits vertical movement enabling proper spacing of the upperand lower terminals to assure optimum electrical contact and facileoperation of the fuse cut-out. It will further be noted that back plate103 is slightly curved to allow it to conform to the contour of theouter periphery of insulator 1.

Two side plates 105 and a cover plate 106 abut back plate 103 at rightangles thereto and are preferably rigidly joined by fillet welds (notshown). Side plates 105 have their lower margins 105a cut upwardly in agenerally arcuate shape to permit ready access for making an electricalconnection with the split bolt connector 126. Of course, the side plates105 and cover plate 106 are preferably stamped as a single piece andbent thereafter to form the desired assembly.

A front plate 107 is welded to the ends of side plates 105 and cover 106in a plane substantially parallel to back plate 103 spaced at theopposite ends of said plates as shown in Fig. 2.

It will here be especially noted that the entire upper contact support101 can be made of a comparatively poorly conductive ferrous metalhaving good corrosion resistant qualities such as the commonly knownCor-Ten. Coating the metal by hot-dipping in a suitable galvanizingmetal is generally desirable to enhance corrosion resistance and toimprove the appearance of the contact support. Note also that thecontact support is not required to act as a conducting member for theprincipal current carried by the fuse cut-out, thereby justifying theuse of ferrous metals.

Front plate 107 is provided with a horizontally disposed elongated hole108 and notches 109 for allowing passage therethrough of a contactspring 112 preferably fabricated of hard-drawn copper and having acircular cross section as shown in Fig. 3.

An alternative type of upper contact support 135 is shown in Figs. 6 and7. It comprises a single piece of corrosion resistant metal having aback plate 136 and an elongated mounting hole 137 similar to those partsreferred to by 103 and 102 respectively in the other views. The topplate 138 is integral with the back plate 136 and has a portion bentarcuately to form a lateral groove 139 defining a bearing point 140 atits under side. The front plate 141 depends from the top plate 138 andis integral therewith. Plate 141 has notches 142 and 143 cut into itsmargins to receive contact spring 112. A reinforcing strap 130 may beriveted or brazed to front plate 141 and top plate 138 as shown and saidstrap 130 may have a hooked-end 131 to freely hold spring 112. The endsof spring 112 bear upon the point 140 and also reside within an arcuatedepression 142a in notch 142 thereby limiting their vertical movement.The lower portion of spring 112 passes through the lower notch 143freely, thereby permitting resilient vertical movement and pressureagainst contact rod 95 as seen in Fig. 1.

Spring 112 consists of a long rod bent symmetrically about its midpoint113 to form an approximate U-shape having two legs 114 which arecurvately bent back upon their own lengths at a point 116 intermediatetheir ends 115 and midpoint 113. Each leg 114 is kinked in laterallyopposite directions outwardly in the same plane at a point 117 to definea widened mouth 118 having converging sides to function as verticalaligning means when the upper fuse contact 86 is swung to closedposition. Leg 114 is given an additional offset bend 119 to define alatching and contact surface 120 which functions as a retaining means tohold contact rod 95 in electrical and mechanical engagement with springcontact 112.

Legs 114 may carry a bifurcated bolt connector 126 which is retainedagainst sliding movement on the legs by protuberances 127 formed byindentation. Connector 126 is usable to connect an incoming hot-linewire (not shown) directly to the contact spring 112 thereby avoidingelectrical conduction through any parts which are relatively movable andsubject to developing high reswa sistance joints due to oxidation orcorrosion .of the parts. it also evident that the circuit'lengtn'nasbeen reduced to abare minimum, resulting in accompanying minimum @1361C3]. res1stance.

from front toward the rear and bears with considerable pressure on theedge 108a causing the entire spring contact 112 to be strongly biased ina downwardly direction.

in the operation of this :fuse cut-out it "will be seen that the lowercontact 56 acts as an intermediate link between trunnion pin 65 and thecartridge contactsupport 45 which in turn holds tube clamp .36. When"the 'cut-out is in closed ,position a conductive fuse .leader '69extends from the lower end of fuse tube and is rigidly 'held thereinagainst longitudinal displacement. The end of the leader 69 is coiledaround shoulder "bolt 76 and held in tension. This'tensile forcetends'to urge the end 70a of the (gas baffle 70 into .tight contactrelation with the fuse tube clamp 36. Hence, the entire lower contact 56is restrained against pivotal movement 1 When the lower linkage isunitarily held by the tensile force of the fuse leader as heretoforedescribed the contact cam "74 carried by the lower contact 56 is urgedinto resilient electrical contact with shunt .29 which is biased towardcam 74 by reinforcing spring 27. Both cam '74 and shunt 29 arepreferably silver plated to minimize electrical resistance therebetween.The cur- ;rent through the fuse cut-out then follows the lowestresistive and most direct path from the fuse leader 69 to the bolt '76and cam 74, through one 'wipin'g joint between cam 74 and shunt '29 anddirectly to the bifurcated bolt connector 24 to the external 'load line(not shown).

It is to be noted that the invention avoids having any electricalcurrent of appreciable magnitude being conducted through parts which aremerely pinnedfor pivotal connection therebetween. 'When'the entire fusetube 35 is pivoted on trunnions 65 to closed circuit position it is tobe observed that said trunnions are strongly biased into bearingrelation in the trunnion receiving surfaces :12 by the coercive forceproduced by :the reinforcing spring .27 urging shunt 29 against cam'7'4.This positive bearing action prevents a lateral rocking on the trannions65 as effectively as if the trunnions resided in a completely enclosedbearing.

Proper vertical alignment of the fuse tube is -further assured whileswinging into closed position .by having the sides 46 of the cartridgecontact support enter the flared entrance 16 of the slot 1'5 in thecover plate .13 of the lower hinge. Since the width of the slot .15 .isonly slightly greater than the space separating the sides 4'6, saidsides are unable to shift laterally and a smooth sliding guidance isestablished. Proper lateral guidance is established at the upper end ofthe fuse tube 35 simultaneously by cooperation of guide pad 96 withcontact spring 112 as will be elaborated upon in an ensuing paragraph.

To pivot the entire fuse tube .35 on trunnion it is necessary to engagethe hook-eye 93 with an insulated stick (not shown) and swing the tube35 therewith to closed position. It will then be noted that cap threadedto upper fuse contact 86 normally protrudes in a generally upwarddirection between the legs 114 of upper contact spring 112. Should afusible section (not shown) within the fuse tube 35 rupture with anaccompanying excessive gas pressure the cap.90 would fracture to releasethe pressure. Of course, a non-frangible cap may also be used. Then uponrupture of the fusible section hot gases are expelled from the lower endof fuse tube 35 and are deflected so as to avoid damage to the lowercontact by gas baffle 70.

Hook 131 is further bent *toward When the fuse tube 35 is pivoted to.closed circuit position as -.descrioedin the last paragraph it carrieswith 1t the upper ruse :contact "156 and its 111011181 member 87.Tubular member 87 has a web '94 :having integral there- "with a guidepad 96 with shoulders 97 ad oining a con- "tact ron '95. an the closingoperation, the guide pad "shoulders9'7 enter the mouth 1rd of contactspring 112 to'thereby centrally align the fuse tube 35 coincidentallywith a "vertical plane taken through insulator 1. Aspreviouslydescribed, lateral guidance is established'atthe lower end offuse tube 35 "by entrance of support 4'5 into slot 15. "Lateralstability of fuse tube is further assured by the positive seating of thetrunnions 65 into the receiving'porti'on 12 caused -by the'force'of'spring 27 against cam 74 when the cut-out nears closedposition. Further pivotal movement causes the outer per'iphery of thecontact rod to drop into the oifset at 119 and to bear in high pressureengagement against the curvate contact area .120 on spring 112. Thiscurvate area 120 also acts to prevent the contact rod from re- "l'easingitself from closed circuit position.

Eurther inward movement of the contact rod 95 is prevented by itsabutting against the front plate 107 "of upper contact support 101.

Attention is called to .the simplicity of connecting *the incoming livewire (not :shown) to the upper contact spring 112 by 'a directconnection thereto by means :of

bifurcated bolt connector '126. This, of course, effects a reduction "inresistance because the current is not required to flow throughrelatively movable parts having high resistance joints.

It is to be appreciated that upper contact spring 112 normally exerts a"tremendous vertical pressure on contact rods '95 when thefuse tube 35is in closed position. This force is developed by reaction of the ends115 of contact spring :112 against the upper edge "103m of elongatedhole MP8 in front @plate 167 as s'hownin Fig. 1 andagainst bearingpointas shown in Fig. 7. When the fusible section within the fuse tube 35ruptures the tension on its "leader is relieved as is the counterforceholding contact rod 95 against curvate shoulder .120. Spring 112 thenbiases the fuse 35 downwardly to released position. After a short delaythe cartridge contact support 45 'collapsibly pivots onpin 55 causingthe lower contact to pivot simultaneously on trunnions 65.

The end .70a of gas baffle '70 swings radially "when the tensile stresson fuse leader 69 is relieved to remove the fuse leader from the tube35. Thereafter the entire fuse cut-out swings on trunnions '65 to opencircuit 'position.

it is claimed:

"1. In a fuse cut-out comprising an insulating support having an upperand lower terminal, an expulsion fuse tube pivotally mounted on thelower terminal for swinging into electrical engagement with the upperterminal, a fuse link in said tube electrically connecting saidterminals, said fuse link extending from the .lower end of said tube,the combination of a pivot support on said lower terminal comprising ahood-like member having relatively spaced hook-like bearings, the topofsaid hood- "like member having 'a slot flared outwardly in ahorizontal direction toward the lower end of said fuse tube in a ,planecoincident with the path of swinging movement of said fuse tube, asupport member secured to and embracing the lower end of said tube andhaving an "extension .proje'cting later-ally of said tube and into saidslot on said hood prior to electrical engagement of the fuse tube by theupper terminal, a pivot link member pivotally connected to saidextension and having trunnions disposed in said hook-like bearings, saidlink member normally disposed in said hood-like member and held againstpivotal movement through the medium of said fuse link, a contact camcarried by said link member, a shunt attached to said hood-like member,resilient means for biasing said shunt into contact relation with saidcam and for urging said trunnions against said hook-like bearings and agas baffle on the link member normally engaging the support memberadjacent the lower end of the fuse tube.

2. In a fuse cut-out comprising an insulating support having an upperand lower terminal, an expulsion fuse disposed between said terminals, afuse link in said tube electrically connecting said terminals, said fuselink extending from the lower end of said tube, the combination of apivot support on said lower terminal comprising a hood-like memberhaving relatively spaced hooklike bearings, the top of said hood-likemember having a slot flared outwardly in a horizontal direction towardthe lower end of said tube, a support member secured to and embracingthe lower end of said tube and having an extension projecting laterallyof said tube and into said slot on said hood, a pivot link memberpivotally connected to said extension and having trunnions disposed insaid hook-like bearings, said link member normally disposed in saidhood-like member and held against pivotal movement through the medium ofsaid fuse link, a contact cam carried by said link member, a shuntsupported by said lower terminal, a spring superposed upon said shuntfor biasing said shunt into contact relation with said cam and forurging said trunnions against said hooklike bearings, and a gas battleon said link member normally engaging the support member adjacent thelower end of said tube.

3. In a fuse cut-out comprising an insulating support having an upperand lower terminal, an expulsion fuse tube disposed between saidterminals, a fuse link in said tube electrically connecting saidterminals, the combination of a pivot support on said lower terminalcomprising a hood-like member having relatively spaced hooklikebearings, the top of said hood-like member having a slot flaredoutwardly in a horizontal direction toward the lower end of said tubeand serving as a lower guide entrance, a support member secured to andembracing the lower end of said tube and having an extension projectinglaterally of said tube and into said slot in said hood, a pivot memberconnected to said extension and having trunnions disposed in saidhook-like bearings, said pivot member normally disposed in saidhood-like member, the upper terminal comprising a bonnet-like member, aspring contact supported by said bonnet-like member and having laterallyspaced relatively resilient leg portions flared outwardly of each otherfrom said bonnet and serving as an upper guide entrance, a contactcarried by the upper end of said fuse tube and having a guide padintegral therewith provided with opposed shoulders slidably receivablein said upper guide entrance, whereby said upper and lower guideentrances cooperate to maintain said fuse tube in vertical alignmentwith said upper and lower terminals when said tube is being pivoted onits pivot support.

4. In a fuse cut-out comprising an insulating support having an upperand lower terminal, an expulsion fuse tube disposed between saidterminals and pivotally mounted on said lower terminal for swingingmovement relative to said upper terminal, the combination of a springcontact support comprising a bonnet-like member having upper and lowerentrances on one end thereof, a reinforcing member rigidly connected tothe top and said one end of said bonnet-like member and having a wirereceiving arcuate portion adjacent the other end of said bonnet-likemember, a U-shaped spring contact comprising a resilient wire bentintermediate its ends to form a base portion disposed in said arcuateportion, substantially parallel leg portions on said spring contactextending through said lower entrances, the outer ends of the wire beingbent outwardly and backwardly to provide a guide entrance and springanchoring portions extending into said upper entrances, said legportions each having an offset portion serving as a latching elementadjacent said lower entrances of said one end of said bonnet-likemember, a contact rod carried by the upper end of said fuse tube spacedlaterally from the axis of said tube and yieldingly engageable with saidspring contact at said offset portion when said fuse tube is swung toclosed position against the one end of said bonnet-like member, a guidepad intermediate the ends of said contact rod and having shouldersslidably receivable within said guide entrance of said spring contact.

5. In a fuse cut-out comprising an insulating support having an upperand lower terminal, an expulsion fuse disposed between and electricallyconnecting said terminals and pivotally mounted on said lower terminalfor swinging movement relative to said upper terminal, said upperterminal comprising a bonnet-like spring contact support having upperand lower entrances at one end, a reinforcing member rigidly connectedto the top of said support adjacent the other end thereof and to saidone end, said member having a wire receiving arcuate portion adjacentsaid other end of said support, a U-shaped spring contact comprising awire bent intermediate its ends to form a base portion disposed in saidarcuate portion at said other end of said support, substantiallyparallel leg portions on said spring contact extending loosely throughsaid lower entrances, the outer ends of said spring contact being bentoutwardly and backwardly and loosely extending through said upperentrances, said leg portions each having an offset portion serving as alatching element adjacent said one end of said support, a contact rodcarried by the upper end of said fuse tube electrically engageable withsaid latching element when said fuse tube is swung to closed position,and a line connector connected to said spring contact whereby a line maybe clamped directly to said spring contact and engaging surfaces of thesupporting structure are electrically bypassed.

6. In a fuse cut-out comprising an insulating support having an upperand lower terminal, an expulsion fuse disposed between and electricallyconnecting said terminals and pivotally mounted on said lower terminalfor swinging movement relative to said upper terminal, said upperterimnal comprising a bonnet-like spring contact support having anentrance at one end, a reinforcing member rigidly connected to the topof said support adjacent the other end thereof and to said one end, saidmember having a wire receiving arcuate portion adjacent said other endof said support, a U-shaped spring contact comprising a wire bentintermediate its ends to form a base portion disposed in said arcuateportion at said other end of said support, substantially parallel legportions on said spring contact extending through said entrance, theouter ends of said spring contact being bent outwardly, said legportions each having an offset portion serving as a latching elementadjacent said one end of said support, a contact rod carried by theupper end of said fuse tube electrically engageable with said latchingelement when said fuse tube is swung to closed position, and a lineconnector connected to said spring contact whereby a line may be clampeddirectly to said spring contact and engaging surfaces of the supportingstructure are electrically by-passed.

Schultz Jan. 11, 1949 Yonkers Jan. 3, 1950

